Correlation of Clinical Risk Factors with Diffusion-Weighted Magnetic Resonance Images in Prostate Cancer Patients Treated with Definitive Radiotherapy

Abstract

This study is aimed to correlate apparent diffusion coefficient (ADC) values and clinical T-stage, serum PSA, pathology Gleason scores. We also further analyzed whether ADC values could be used to appropriately define the risk groups. 135 biopsy-proven, radiotherapy-(RT)-treated, prostate cancer patients who underwent pre-RT DW-MRI and standard T2W pelvic MRI were included. ADC and normalized ADC (nADC) values were calculated from DW-MRI delivered a median 8.1 weeks after prostate biopsy. ADC values were correlated with clinical risk factor values by using Pearson correlation test. ADCs in low-, intermediate-, and high-risk patients were 0.873 +/- 0.122X10(-3) mm(2)/s, 0.763 +/- 0.124X10(-3) mm(2)/s, and 0.701 +/- 0.132X10(-3) mm(2)/s (p = 0.001), respectively. Patients with preRT PSA <10 ng/mL had significantly higher ADCs than patients with preRT PSA 10-20 ng/mL (p = 0.02) or >20 ng/mL (p < 0.001). Mean ADC for patients with Gleason score <7 was significantly higher than patients scoring 7 (p = 0.001) or >7 (p < 0.001). Clinical stage <T2b patients had significantly higher ADC values versus stage T2b (p = 0.001) and T2b tumors (p < 0.001). ADC demonstrated stronger correlation with NOON risk groups (R = -0.510; p < 0.001). All clinical factors except Gleason score had moderate inverse correlation with nADC. Best nADC correlation occurred with NOON risk groups (R = -0.461; p < 0.001). ADCs measured by DW-MRI are noninvasive prognostic markers of clinical parameters and risk for prostate cancer in RI candidates.